El Nino, Global Warming, and Anomalous U.S. Winter Warmth

It has now become all too common. Peculiar weather precipitates immediate blame on global warming by some, and equally immediate pronouncements by others (curiously, quite often the National Oceanic and Atmospheric Administration in recent years) that global warming can’t possibly be to blame. The reality, as we’ve often remarked here before, is that absolute statements of neither sort are scientifically defensible. Meteorological anomalies cannot be purely attributed to deterministic factors, let alone any one specific such factor (e.g. either global warming or a hypothetical long-term climate oscillation).

Lets consider the latest such example. In an odd repeat of last year (the ‘groundhog day’ analogy growing ever more appropriate), we find ourselves well into the meteorological Northern Hemisphere winter (Dec-Feb) with little evidence over large parts of the country (most noteably the eastern and central U.S.) that it ever really began. Unsurprisingly, numerous news stories have popped up asking whether global warming might be to blame. Almost as if on cue, representatives from NOAA’s National Weather Service have been dispatched to tell us that the event e.g. “has absolutely nothing to do with global warming”, but instead is entirely due to the impact of the current El Nino event.

[Update 1/9/07: NOAA coincidentally has announced today that 2006 was officially the warmest year on record for the U.S.]
[Update 2/11/08: It got bumped to second place. ]

So what’s really going on? The pattern so far this winter (admittedly after only 1 month) looks (figure on the immediate right) like a stronger version of what was observed last winter (figure to the far right–note that these anomalies reflect differences relative to a relatively warm 1971-2000 base period, this tends to decrease the amplitude of positive anomalies relative to the more commonly used, cooler 1961-1990 base period). This poses the first obvious conundrum for the pure “El Nino” attribution of the current warmth: since we were actually in a (weak) La Nina (i.e., the opposite of ‘El Nino’) last winter, how is it that we can explain away the anomalous winter U.S. warmth so far this winter by ‘El Nino’ when anomalous winter warmth last year occured in its absence?

The second conundrum with this explanation is that, while El Nino typically does perturb the winter Northern Hemisphere jet stream in a way that favors anomalous warmth over much of the northern half of the U.S., the typical amplitude of the warming (see Figure below right) is about 1C (i.e., about 2F). The current anomaly is roughly five times as large as this. One therefore cannot sensibly argue that the current U.S. winter temperature anomalies are attributed entirely to the current moderate El Nino event.

Indeed, though the current pattern of winter U.S. warmth looks much more like the pattern predicted by climate models as a response to anthropogenic forcing (see Figure below left) than the typical ‘El Nino’ pattern, neither can one attribute this warmth to anthropogenic forcing. As we are fond of reminding our readers, one cannot attribute a specific meteorological event, an anomalous season, or even (as seems may be the case here, depending on the next 2 months) two anomalous seasons in a row, to climate change. Moreover, not even the most extreme scenario for the next century predicts temperature changes over North America as large as the anomalies witnessed this past month. But one can argue that the pattern of anomalous winter warmth seen last year, and so far this year, is in the direction of what the models predict.

In reality, the individual roles of deterministic factors such as El Nino, anthropogenic climate change, and of purely random factors (i.e. “weather”) in the pattern observed thusfar this winter cannot even in principle be ascertained. What we do know, however, is that both anthropogenic climate change and El Nino favor, in a statistical sense, warmer winters over large parts of the U.S. When these factors act constructively, as is the case this winter, warmer temperatures are certainly more likely. Both factors also favor warmer global mean surface temperatures (the warming is one or two tenths of a degree C for a moderate to strong El Nino). It is precisely for this reason that some scientists are already concluding, with some justification, that 2007 stands a good chance of being the warmest year on record for the globe.

A few other issues are worthy of comment in the context of this discussion. A canard that has already been trotted out by climate change contrarians (and unfortunately parroted uncritically in some media reports) holds that weather in certain parts of the U.S. (e.g. blizzards and avalanches in Colorado) negates the observation of anomalous winter warmth. This argument is disingenuous at best. As clearly evident from the figure shown above, temperatures for the first month of this winter have been above normal across the United States (with the only exceptions being a couple small cold patches along the U.S./Mexico border). The large snowfall events in Boulder were not associated with cold temperatures, but instead with especially moisture-laden air masses passing through the region. If temperatures are at or below freezing (which is true even during this warmer-than-average winter in Colorado), that moisture will precipitate as snow, not rain. Indeed, snowfall is often predicted to increase in many regions in response to anthropogenic climate change, since warmer air, all other things being equal, holds more moisture, and therefore, the potential for greater amounts of precipitation whatever form that precipitation takes.

Another issue here involves the precise role of El Nino in climate change. El Nino has a profound influence on disparate regional weather phenomena. Witness for example the dramatic decrease in Atlantic tropical cyclones this most recent season relative to the previous one. This decrease can be attributed to the El Nino that developed over the crucial autumn season, which favored a strengthening of the upper level westerlies over the tropical North Atlantic, increased tropical Atlantic wind shear, and a consequently less favorable environment for tropical cyclogenesis.

If a particular seasonal anomaly appears to be related to El Nino, can we conclude that climate change played no role at all? Obviously not. It is possible, in fact probable, that climate change is actually influencing El Nino (e.g. favoring more frequent and larger El Nino events), although just how much is still very much an issue of active scientific debate. One of the key remaining puzzles in the science of climate change therefore involves figuring out just how El Nino itself might change in the future, a topic we’re certain to discuss here again in the future.

Is there any possibility that you have an address for the picture with the effect on temperature by El Nino, or a larger picture?

(thanks again for a great blog)

[Response: Sorry, should have included that. You can actually ‘custom build’ a composite on this NOAA site, choosing the region, season, type of event (El Nino vs. La Nina), etc. Unfortunately, you can’t change the base period :( -mike]

The US is not the world – I’ve heard from various people that Europe seems to be experiencing an even more anomalously-warm winter this year – no snow in Norway & Sweden, crocus blooming at Christmastime in Germany, etc. Indeed, it almost seems that I’m in one of the few places (northern Nevada) that’s having fairly normal winter temperatures. Care to expand/comment on this?

[Response: I confess that the resources I rely upon (e.g. NOAA’s web pages) don’t provide up-to-date global temperature information. Perhaps some of my European RC colleagues can help out here? -mike]

Eastern Siberia has had a large area in the last several days which are below -50C. The really, really cold air has just moved to eastern Siberia rather than central northern Russia. The stormy weather of El Nino has hit Oregon and British Columbia rather than California. The cold water pattern in the north-western Pacific is exactly the same as the above graphic. The north Atlantic warm pool is exactly the same. North American temperatures are similar.

Most of the scientific observation and analysis of ENSO was since 1976 and as a result, during a positive PDO phase. PDO has been behaving erratically since 1997 or 98 (some suggest it may want to flip negative). What should we expect due to ENSO during a negative phase PDO? Perhaps the period 1940 – 1976 might provide clues. At some point we’ll probably be able to characterize it better. Then the final food for thought, what sorts of even higher order, longer period things might be going on in terms of these SST anomaly oscillations? Is there something with an even longer period than the PDO that we simply don’t yet recognize because the pre 1940 data are not sufficient to reveal it? And all of this superimposed on even longer term changes.

#2 Not really an RC colleague :D but I confirm (from France) that west-European winter is unusually warm, even if december anomalies are a bit less pronounced than sep-nov (fall) ones (in France, the warmest fall since 1950, beginning of homogeneized daily measures, and probably since 1865 ; in Austria, Germany, Spain, Portugal… +1,5 to +4Â°C, snowfall deficit in all the Alpin region, etc.). Previous works (eg Moron et Plaut 2003) find an El Nino influence on European fall-winter weather, with a zonal mode dominant on nov-dec (warm and wet flux from Atlantic) and with a higher probability of a switch on west blocking or Greenland anticyclone regimes on feb-march. But correlations are not causations, weather conditions are more chaotic (and the present El Nino is weak).

RE: #2 – RE: The European drought (and warmth in the SW quadrant of Europe). So here is an image of current snow cover and sea ice. Southern Sweden is drought ridden (but yet cold enough for some shore fast / near shore sea ice nearby in the usual places). Northern Sweden and much of Norway have coverage. The coverage along the Western shore was greater during the fall and had since melted / sublimated away. The rest Western Europe is in a bad way and will need to get lots of snow / rain between now and mid year to get out of trouble.

A difficult point for me is : in what way can we partly attribute all phenomena (even a local cooling) to AGW (and if so, is there any sense for this kind of attribution)? Small changes in oceanic or atmospheric circulation due to small changes in radiative equilibrium may translate in flooding here and drying there, warming here and cooling there, etc. So, we allways need a long term trend (30 yrs) to assert a significative change, a potential link with AGW and a more-or-less good conformity with models’ predictions. Where are we now for 1977-2006 trends in the USA winter?

Sounds like NOAA’s pronouncement is distinctly unempirical, because if records are being broken over your way like they are here in Europe, then by definition that is not evidence of a cyclic description.

From the point at which detailed records begin, you can always expect new records to break old ad infinitum in a chaotic system, but if there were no inherent trend then the rate of record-breaking for a finite set of annual indicators would tend to decay with a zero asymptote.

As regards Katrina, although were it not for AGW a hurricane as damaging as Katrina might have occurred if one were to wait long enough, surely Katrina itself was made more damaging by AGW as that was a factor contributing to Caribbean SSTs and the local tropospheric vertical temperature gradients at that point in time?

Have you and the US weather service been using a 10 year running average to compare higher and lower than “normal” temperatures? You and the US weather service need to set a period of time in the past as the “normal” period so that “normal” doesn’t change every year. The century from 1850 to 1950 seems appropriate. Against the century from 1850 to 1950, has the past half century been warmer?

Actually, there were significant deviations before then. It was the winter of â��84 that I stood on the Point near Port Washington, Wisconsin the day before New Years Eve in a brisk breeze and 60 Deg. F dangling my feet in the chilly water. A week later around the 10th of Jan. 1985, I was climbing over ice floes on the shore of Grand Haven Michigan, watching pot ice form in the Grand River.

re: 11. The statistical “normals” for climate data are 30-year periods, not 10-year running averages. For example, 1961-1990, 1971-2000, etc. However, they are 30-year blocks, not 30-year running averages. Generally in the eastern US, the 1961-1990 30-year normals are cooler than the 1971-2000 normals. Many will recall how snowy the 1960s were in particular.

Most important, the word “normal” here is a statistical calculation/definition. It does not mean normal as the word is used in common speech. In fact, in my city, today’s statistical normal daily maximum temperature of 46 degrees F rarely actually occurs since that value is based on the daily maximum temperatures from each January 8th during the period from 1971-2000. In other words, the daily maximum temperature for each of those January 8th days is summed up and divided by 30.

A 30-year period was determined to represent the statistical normal through various analyses. I beleive there is more detail at the National Climatic Data Center web site which is easily found via Google.

Regarding the comments on the VERY warm winter in Scandanavia – my wife is a Finn. She is currently in Vaasa. Vaasa is not too far below the Arctic Circle. This morning, she called me to say that it is raining non-stop, the grass is green and, in the park yesterday, she saw tulips pushing up.

Of course no one weather incident can be proven to be the result of any other one single factor, global warming or el nino. However it seems like saying that this latest anomoly fits the pattern we would expect from anthropormophic climate change, would be very useful and scientifically correct. I’m just a layman, but while denying direct correlation is correct, saying that what we are seeing fits the computer model predictions (even if it is more extreme than most predictions) would also be just as correct and more politcally useful.

A surface temperature anomaly map by NASA for 2001-2005 shows that the warmest regions occurred over northern high latitude land mass areas, exactly what global climate modelers had predicted many years ago.

2006 annual mean temperatures at climate stations in Montana, North Dakota and Minnesota were near or exceeded the warmest years of record (1890s-current).

Based on things that we know, it seems irresponsible to me that some people continue to try to credit mainly El Nino for many of the warming conditions which we know have been happening for many years. Come on folks, wake up! It’s obvious.

Why is it mid January and now we are all beginning to hear of el-nino as the culprit of this “new” weather we are having? It is extremely after the fact, and a monkey could deduce this fact as late as it is. Save some water, same some food, and eat drink and be merry, for tomorrow we die. I swatted a mosquito on my back door today, did I say I was in central PA? What happened to Jack frost whipping in the house as I opened the door? no, I am going out without a coat.

In Reply to comment 9: “A difficult point for me is : in what way can we partly attribute all phenomena (even a local cooling) to AGW …?”

If the analysis was scientific as opposed to political, other factors would be considered and discusssed. For example solar (Note the current solar activity is very, very, unusual). See the attached paper that shows there is a significant correlation of average planetary temperature and the solar index-ak. (See attached for details as to what ak measures, also check out the Solar Terrestrial Activity Report. The Dec 16, 2006 spike is what the paper is describing.)

The following is an excerpt from the conclusions (Short paper. Difficult for scientific discussions without facts.)

“It could therefore be concluded that both the decreasing correlation between sunspot number and geomagnetic activity, and the deviation of the global temperature temperature long-term trend from solar activity as expressed by the sunspot index are due to the increased number of high speed streams of solar wind on the decreasing phase and the minimum of sunspot in the last decade.”

Comments:
1. The high speed solar wind (during the solar cycle minimum) has increased the net charge in the ionsphere. (Normally the ionsphere can discharge during the solar minimum and there is less charge to discharge.)
2. As a result of the increased charge in the ionsphere, the newly observed phenomena called “Sprites” (a discharge from ionsphere to cloud tops) has been observed starting in about 1993. Sprites can and have destroyed aircraft.
3. It is assumed that this solar driven phenomena is the reason why there is a reduction in low level clouds. See attached paper by Palle. Palle found there is a 99.9% oorrelation of GCR to cloud cover 1983 to 1993. From 1993 and on there is an anomalous reduction in low level clouds. Where have all the low level clouds gone?

What can I say, most excellent post, and also great remarks from RC bloggers, Eastern Siberia is it, we are sharing some of its cold, it is eerily like the winter of 2005-06 except its warmer, I might add what I wrote last November, this winter will be like fall with the occasional visit from winter. One must remember, the temperature mean is pushed upwards, but natural variations from the mean predicts some cold is bound to come, but not to last for very long.

Reference book: “The Way to Win, Taking the Whitehouse in 2008” by Mark Halperin and John F. Harris, 2006
The referenced book makes many references to http://www.drudgereport.com. The Drudge Report is where the “Freak Show” happens. The freak show is bad journalism that causes the best candidate to loose the election for president.
You are battling the “Freak Show”. Many of the readers and commenters at that level have such poor reading comprehension that they will never understand you. Don’t try to accomodate them, they really don’t want to understand. But they Would enjoy making fun of a degreed person. If you answer them, don’t use your real name.
“The Way to Win” also mentions many times that people are INSTINCTIVELY conservative. Take that literally. Management hasn’t changed much in the past 30 Million years. People still look to the president to be the Alpha Male.

Many of these explanations also apply to explain why the ‘winter’ has not yet ‘arrived’ in Northern Europe. December was record-warm in many parts of southern Norway, ann the autumns has been record-warm over extensive regions of Northern-Europe.

What is astonishing to me is that El Nino is caused by abnormally warm Pacific ocean SST (surface sea temperature), and higher SSTs are quintessencial global warming, so why does NOAA (the National Oceanic and Atmospheric Administration) seek to disassociate El Nino from global warming?

In other words, what is the hidden motive of NOAA to deny global warming and higher SST? Sooner or later the increased severity of hurricanes (which are already twice a strong due to higher SST), and increased frequency and severity of El Nino, will have to be called what they are: manifestations of global warming.

I work for the US military in the German Alps. Despite the facts that we have had virtually no snow this year and that the grass is spring green in January – in a ski resort – and the temperature tomorrow is predicted to be 15-18 C, many of my colleagues, indoctrinated by army-provided Fox News and Rush Limbaugh, deny that global warming is taking place and continue to drive their huge gas guzzlers with no qualms. The Germans (and the thinking Americans here) are astounded and dismayed at how far media political indoctrination can go in helping people to ignore what is happening right before their eyes.

You say that the current anomalies in the US are well beyond the most extreme predictions from climate models, suggesting that the the chaotic nature of weather events must play a role, too (though within an overall warming trend).

What really concerns me is that I’ve read a lot about climate models not being able to replicate the magnitude of abrupt regional temperature changes in the past, and Raypierre has said here that he fears that past climate records point towards some yet unknown positive feedback which might amplify warming at the northern latitudes.

My feeling in Scotland is that the changes to the weather (ie where the wind comes from) are far more dramatic than the background warming. When we do get northerly winds they are probably less cold than they were 15 years ago but that’s far harder to notice than the fact that we now tend to get southerly or south-westerly winds nearly all of the time.

Could we be looking at any fairly abrupt changes to the jet stream, possibly triggered by sea ice melting or stratospheric changes? Has anybody looked at whether the jet stream has behaved ‘abnormally’ over the past few years?

About the winter in Finland: December was the warmest measured in a large part of the country. Deviations from the 1971-2000 climatology were 6-8 degrees (C). I don’t know how many sigmas that is, but local news cited “two times in thousand years” – and the reference period includes warm winters of 90’s! The situation is pretty much similar for the whole Scandinavia, including northern parts of Russia west of Ural. The beginning of January has been about equally warm, and the models do not show an immediate (7-14 days) cooling.

From the newspapers one get the feeling that with respect to global warming, this has been the strongest wake-up call so far. People have been aware and mostly believing in AGW in a theoretical sense, but now it is concrete that something strange is really happening. The exceptionally dry past summer amplifies the feeling.

By the way, Vaasa is not exactly close to the Arctic Circle, at least not from our point of view. :) Instead, it is close to the seashore in south-west Finland. Finnish Arctic Circle currently has about 40cm snow. But it is true that in the south we have seen some quite strange effects in nature.

I don’t think ENSO can be blamed of our warmth. AO and NAO have been positive, but nothing extraordinary. I wonder if the (lack of) Arctic ice cover is somehow involved.

Tobacco, asbestos, radiation and most health hazards have been hiding themselves for many years behind the fact that you cannot assign a single cause as determinant to a single effect: you cannot prove a single cancer has been caused specifically by that person’s smoking habit (or work environment, or whatever lethal cause is suspected).

It took years and and overwhelming amount of statistical data to revert these statements, which caused numerous deaths of individuals.

Do we need to wait until statistics also justify the underlying causes of numerous disasters affecting society all over the world?

We know things are going the wrong way, and almost everything we see corresponds to that view. What more do we need to get some action?

Koen, I think we’ll need to see some very painfull events to wake up, much more painfull than Katrina.

Good news is many people are waking up, at least in Spain and I think this is quite common around Europe. It’s just obvious climate is wrong. I just can’t remember a normal year here. It’s been hot since last week of February until December, then one week of colder weather and it’s hot again. My tomato plants are growing like weeds when they should be barelly alive. In the mountains, trees have gone up hundreds of meters… We are used to variable weather, but not to constantly variable.

In Switzerland, current January temperatures are 5-6 degrees C above the mean (1961-90), and current weather forecasts do not show any hint for a change for the next two weaks. Last fall set a new temperature record for the instrumental period (since 1864) which was about one degree C above the previous record (three months mean). July 2006 was the warmest month ever in the instrumental period.

– 2006 is shaping up to be the the hottest year since records were kept (1659)

England Mean Temperature Series (series began in 1914). The provisional mean value for the month of December is 6.1 °C 1.8 °C above the 1961-1990 average, which is in the well above average category.

– we haven’t had a winter yet, here in London. I’m not even sure we’ve yet had a frost. Flowers are blooming and there are migratory birds in evidence (3 months early). Average temperature would seem to be about 5 degrees centigrade above normal. It’s 13 degrees centigrade today, London in January is normally betwen 0 and about 8 degrees. Also we have near record gales forecast, and we had a tornado last month in North London (a very rare occurrence)

2007 is likely to be the warmest year on record globally, beating the current record set in 1998, say climate-change experts at the Met Office.

Each January the Met Office, in conjunction with the University of East Anglia, issues a forecast of the global surface temperature for the coming year. The forecast takes into account known contributing factors, such as solar effects, El Nino, greenhouse gases concentrations and other multi-decadal influences. Over the previous seven years, the Met Office forecast of annual global temperature has proved remarkably accurate, with a mean forecast error size of just 0.06 °C.

Met Office global forecast for 2007

* Global temperature for 2007 is expected to be 0.54 °C above the long-term (1961-1990) average of 14.0 °C;
* There is a 60% probability that 2007 will be as warm or warmer than the current warmest year (1998 was +0.52 °C above the long-term 1961-1990 average).

The potential for a record 2007 arises partly from a moderate-strength El Nino already established in the Pacific, which is expected to persist through the first few months of 2007. The lag between El Nino and the full global surface temperature response means that the warming effect of El Nino is extended and therefore has a greater influence the global temperatures during the year.

Katie Hopkins from Met Office Consulting said: “This new information represents another warning that climate change is happening around the world. Our work in the climate change consultancy team applies Met Office research to help businesses mitigate against risk and adapt at a strategic level for success in the new environment.”
Review of 2006 in the UK

This startling forecast follows hard on the heels of news that 2006 was the warmest year on record across the UK.

For 2006, all UK data have now been gathered, revealing a similar story to that of Central England Temperature already announced last month.

Autumn 2006 (September to November) was also exceptionally mild over many parts of Europe at more than 3 °C above the climatological average from north of the Alps to southern Norway. In many countries it was the warmest autumn since official measurements began.

Notes:

* The Met Office is the UK’s National Weather Service, providing world-renowned scientific excellence in weather and climate change.
* Met Office climate change consultancy provides data and risk-management services that are used by other government departments and agencies, the private sector and the public to mitigate and adapt to climate change.
* Met Office Hadley Centre for Climate Change is funded by Defra and the MoD.
* The 95% confidence range of the global forecast is that the temperature will lie between 0.38°C to 0.70°C above normal.

Sitting here in Brussels, the temperature today is around 12degC. Thats 8degC above average for Jan. Global temperatures have risen 0.7degC in 100 years. Thus global warming could explain about 0.4degC of this rise above ‘average’ (5%). Something else must explain the rest.

I don’t know where you’ve been but I heard about this El Nino several months ago and figured this would be warm winter in North America.

Re #20

I wouldn’t characterize the El Nino phenonmenon as abnormal warm water. It’s a natural phenonmenon. The ocean warms and cools on a natural cycle of a few years. The warming phase is called El Nino. There is some evidence that El Nino was even more active during the Little Ice Age. Of course, the real point of this article is El Nino may be making only a small contribution to the current North American warm winter.

I haven’t seen this mentioned yet. Why are the anomalies (this winter) so much colder in eastern Siberia than prediced warmimg models. Are the very cold temperatures normal considering the El Nino and North Atlantic oscillation AND the warming over the rest of the arctic? It looked like the models would show warming in Siberia also when NA and Europe warmed. Thanks for your response.

RE: “But one can argue that the pattern of anomalous winter warmth seen last year, and so far this year, is in the direction of what the models predict.”

Here in Australia, we are getting a “sneak preview” what the CSIRO have been predicting to happen 20-50 years from now. The SE has been suffering the worst drought on record for the past five years. Meanwhile the NW has had enough extra rain to keep the nations average relatively stable. As for extremes of weather we have had heat waves and constant bushfires interspersed with unseasonal frost and snow.

The result is a halving (down 62%) of our grain crop due to lack of rain, a large chunk of fruit crops have died on the vine due to the unseasonal frost. Dairy and livestock herds have also been drastically reduced in the SE due to lack of rain. I hope EL Nino does break our drought because rain falling on the desert instead of the remaining topsoil in the dried up Murry-Darling basin isn’t going to feed anyone (I think we are around the 4th largest grain exporter, a 62% reduction in our grain crop equals a loss of ~17,000,000 tons).

I’m always a bit amused at those who promote AGW, and the media who support them, continue to use emotive, evocative words in their descriptions of mathematic statistical functions of temperatures and/or precipitation data sets. For instance, if it is warmer or colder, it is compared to “normal”, as in a norm or standard or the usual and expected state, when of course it is merely a statistical “average” they really mean. They give us no standard deviations, data distributions, nor other statistical tests, just one word, normal. So why not use the word average, or more precisely, statistical average? I think I know the reason, average doesn’t carry the emotional response that triggers fear and concern like something being abnormal does. Your words tend to prove your motives gentlemen.

Have you ever talked to people — nonscientists — about scientific topics? As soon as you use phrases like “statistical average,” “standard deviation,” “data distribution,” or “statistical tests,” their eyes glaze over and their attention wanders. We use the word “normal” because we’re communicating with lay readers, and that is the language as used by the general populace. When we scientists talk to each other, we use all the “technical” phrases you refer to.

I think I know the reason for your post: your words reveal your motives. How weak is your case, when you must resort to “accusing” us of using the word “normal” in order to incite passion?

You’re amusing too! You missed the explanation above, perhaps? You wouldn’t want people to be confused about this, and saying ‘average’ confuses people as you’re confused about it — ‘normal’ is used in science and medicine — as your doctor should have told you when you had normal lab results on routine medical tests — to mean within 2 sigma.

You don’t want your thyroid or iron or blood pressure to be ‘average’ — you do want it in the normal range. Same for your climate, eh?

Re #43, on using “normal” instead of “average”. It is true that the words are not synomymous: normal implicitly refers to a distribution or a quantile, while average refers to a single number. Sometimes people use these correctly, sometimes not. I would attribute it more to expectations than to motives: if one is seeking deviations, it is natural to speak about “normal”.

Speaking of emotive, “those who promote AGW, and the media who support them” could also read “those who try to educate people about AGW, including some media”. And “Your words tend to prove your motives” could be “Some of you seem to be really worried, and it shows in your language”. It’s really hard to be neutral. :)

I was trained as a (mathematical) physicst but made a career as computer professional. I have had some contact with both large scale computer models and with the scientific establishment. I find RC an interesting read as an AWG skeptic. I think the following quote might add a little perspective to this discussion.

“Like dreams, statistics are a form of wish fulfillment.”
Jean Baudrillard

Re: #44, well said GAW, and as Orwell said, sloppy language leads to sloppy thinking, this subject in spades. Why is it some scientists just can’t use precise, scientifically correct language? Again, your words prove your motives.

RE; #32 – Over the past year or so, the NH extent anomaly has wiggled between just under -1M Km^2 and just over zero. At present, the anomaly is ~ -0.3M Km^2 and somewhat positive trending. As you are probably aware, the Barents Sea and to a somewhat lesser extent the Kara Sea had quite late icing up this year (as opposed to other NH basins which more or less froze up on queue). Another oddity has been the repeated highly compressive (in terms of lateral pressure) events driven by easterly winds, along the ice edge between Svalbard and SE Greenland. Along the NW coast of Svalbard the edge has repeatedly enveloped the shore then been pushed back out by these winds. You comment has piqued my interest, for I have long wondered how a good closure of sea ice to a continental land mass can impact things, witness Actic NE Asia this year.